Coating formulations and their application over various substrates find use in numerous industries, such as, for example, those employing coated coil, coated electronic displays, coated wind blades, and coated automotive components. Coating formulations are usually comprised of thermosetting or thermoplastic materials. Thermosetting formulations typically require high temperatures to cure. Such cure can be costly, both in terms of energy and time. Thus reducing cure temperatures or bake cycles represents a significant opportunity for energy savings. Reduced energy requirements have the added benefit of reducing environmental impact through a reduction in the carbon footprint of the manufacturing process.
Near-infrared (IR) lamps direct energy to coatings by radiative transfer and often use significantly less energy than a process using a convection oven. Additionally, radiative heating is a more rapid process than convection heating. On coil coating lines with convection ovens, for example, typical residence times are 20-30 seconds whereas with near-IR lamps, the typical residence time is 1-4 seconds. Near-IR absorbing materials may reduce required cure temperatures or bake cycles when used in thermoset coating formulations. However, conventional near-IR absorbing additives also impact the visible light absorption and therefore can affect the color of the coating.
Accordingly, the need exists to effectively incorporate infrared absorbing materials into IR cured coating systems enabling reduction in energy consumption while achieving or maintaining the desired appearance and color of the coated object.